This invention relates to a blanket assembly for use as a replaceable cover for the cylindrical anvil of a rotary die cutter or the like to support the sheet or web material being cut by the die or dies carried by the complementary rotary die cylinder, as shown, for example, in our U.S. Pat. No. 4,716,802. The invention has particular relation to a new and improved latch mechanism for securing a die cutter blanket of urethane or other elastically deformable material to a rotary die cutter anvil roll of special construction different from the anvil roll shown in our U.S. Pat. No. 4,848,204.
More specifically, the primary object of the present invention is to provide replacement blankets for use on an anvil roll of a prior art construction illustrated in FIGS. 1 and 2. As shown in those views, the replaceable blanket 10 is mounted on a composite anvil roll comprising an annular metal head 11 surrounded by a two-piece slip bearing 12 of a hard polyurethane although it could also be of metal, and for the purposes of the present invention, the bearing 12 could be integral with the head 11.
In this prior art construction, the bearing 12 is provided in its outer surface with a slot 13 of generally channel shape having opposed parallel side walls 14 and 15 and a flat bottom 16 extending from end to end of the roll parallel with its rotary axis. In addition, each of the side walls 14 and 15 of the slot 13 is provided with a groove 18 along its inner edge which in effect increases the width of the slot bottom 16 and is overhung by the adjacent slot wall 14 or 15.
The blanket cover 10 is molded of elastically deformable urethane, and a sheet metal liner 20 is adhered to its radially inner surface. The opposite ends of this liner 20 carry the complementary members of a latch assembly designed for interlocking engagement within the slot 13. The latch member 22 is riveted to one end of the liner 20 and is of generally channel shape in cross-section proportioned for endwise insertion in the slot 13. The member 22 is provided along its outer edges with rib portions 23 proportioned to be received in the grooves 18 in the side walls of slot 15. The elastomeric material of the blanket 10 extends into a minor portion of the interior of the member 22 and is configured to provide a shoulder 23 facing the bottom wall of member 22.
In use, due to the grooves 18 in slot 13 and ribs 23 on channel 22, the channel must be inserted endwise into the slot 13 and is thereby anchored in the slot before installation of the blanket assembly is completed. The complementary part of the latch assembly is a metal bar 25 riveted to the opposite end of the liner 20 and having its back edge and a portion of its underside covered with a layer 26 of the material of the blanket 10. The outer edge of the bar 22 projects beyond the adjacent end of the liner 20 and the blanket 10, and the bar 25 and its urethane cover 26 are proportioned as a whole so that the projecting edge of the bar will hook under the shoulder 23, and its covering 26 can then be forced into the member 22 to complete the latched engagement.